Iolabs device [http://www.iolab.co.uk/products/index.html] might be better than the Cedrus box detailed below. And there is PsychoPy code available for the Iolabs device.

== The box ==

== The box ==

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The button-box we have used for our "sensorimotor synchronisation" experiments is a Cedrus RB-730 response pad. It is on loan from Nenad and the IT office. It connects to the computer via a USB port, and is controlled by the computer as a serial port (or something like that). [http://www.cedrus.com/responsepads/rb730.htm]. To work, you must install a driver from the Cedrus website here:[http://www.cedrus.com/support/rb_series/tn1057_install_rbx30_macos_x.htm], and surprisingly, I also had to install a USB to serial port driver from a company called Keyspan: [http://www.keyspan.com/downloads/homepage_pn_usa28x.spml]. I used the driver for their USA-28x product.

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The button-box we have used for our "sensorimotor synchronisation" experiments is a Cedrus RB-730 response pad. It is on loan from Nenad and the IT office. It connects to the computer via a USB port, and is controlled by the computer as a serial port (or something like that). [http://www.cedrus.com/responsepads/rb730.htm]. To work, you must install a driver from the Cedrus website here:[http://www.cedrus.com/support/rb_series/tn1057_install_rbx30_macos_x.htm], and surprisingly, I also had to install a USB to serial port driver called keyspanUSAdrvr from Tripplite, formerly Keyspan: [http://www.tripplite.com/en/support/downloads/driver-firmware-downloads.cfm?start=16&txtType=31&txtOS_Type=74]. I used the driver for their USA-28x product.

I had all of the little dip switches in back in the down position.

I had all of the little dip switches in back in the down position.

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== Programming with the box ==

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== Basic programming with the box ==

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Oh. the below was written before I saw Jon Pierce has put [http://www.psychopy.org/reference/psychopy.hardware-pysrc.html code supporting the Cedrus in psychopy], but i think his code is vulnerable to the same problems

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To use the button-box with a python program, we put dipswitches 1 and 2 down so the box used XID (eXperimental Interface Device) communication protocol, which provides timestamps of button press times. Then you need these lines at the start of your code:

To use the button-box with a python program, we put dipswitches 1 and 2 down so the box used XID (eXperimental Interface Device) communication protocol, which provides timestamps of button press times. Then you need these lines at the start of your code:

Retrieve a line triggered event from the box. We trigger a photodetector by drawing on the screen at a known time, and have the photodetector send an event into the box.

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=== Problems ===

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UPDATE: regarding the below problems, it's possible they're all avoided by using the new code that's since been developed at https://github.com/cedrus-opensource/pyxid

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Hisham Abboud of Cedrus says "the code detects button presses and can retrieve the timestamp, but we're currently setting the timestamp to zero because there is some drift in the hardware itself. We will update the code once we know exactly what the time drift is and can compensate for it. The code is also capable of handling two devices at the same time, e.g. a response pad and an SV-1 voice key."

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* Any commands sent to button box occasionally needs to be done more than once before it takes. Box unreliable in this way (although apparently not a problem with code at github link above). Sometimes I have to restart code several times before box will listen

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* If send too long a stream of events (e.g. line in left on), box seems to become unresponsive

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* Sam T tried to do an experiment collecting multiple responses per trial, but seemed that the Cedrus RB-730 measured multiple responses inaccurately, accumulating a timing error of roughly 500ms over a 20-tap-piloting trial.

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Sam T tried to do an experiment collecting multiple responses per trial, but seemed that the Cedrus RB-730 measured multiple responses inaccurately, accumulating a timing error of roughly 500ms over a 20-tap-piloting trial.

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== Timing Precision ==

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== Precision ==

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A file summarizing our tests of the precision of the timing is here [[media:buttonBoxPrecisionSummary.doc]]

A file summarizing our tests of the precision of the timing is here [[media:buttonBoxPrecisionSummary.doc]]

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For on-line, during-experiment timing verification we would like to trigger a photodetector by drawing on the screen at a known time, and have the photodetector press a button on the button box using what? an "Active Switch Closure" lead?

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For on-line, during-experiment timing verification we trigger a photodetector by drawing on the screen at a known time, and have the photodetector trigger an event in the button box.

Another way to verify timing and precision would be with [http://www.blackboxtoolkit.co.uk/ this expensive device].

Another way to verify timing and precision would be with [http://www.blackboxtoolkit.co.uk/ this expensive device].

Other

Iolabs device [1] might be better than the Cedrus box detailed below. And there is PsychoPy code available for the Iolabs device.

The box

The button-box we have used for our "sensorimotor synchronisation" experiments is a Cedrus RB-730 response pad. It is on loan from Nenad and the IT office. It connects to the computer via a USB port, and is controlled by the computer as a serial port (or something like that). [2]. To work, you must install a driver from the Cedrus website here:[3], and surprisingly, I also had to install a USB to serial port driver called keyspanUSAdrvr from Tripplite, formerly Keyspan: [4]. I used the driver for their USA-28x product.

I had all of the little dip switches in back in the down position.

Basic programming with the box

To use the button-box with a python program, we put dipswitches 1 and 2 down so the box used XID (eXperimental Interface Device) communication protocol, which provides timestamps of button press times. Then you need these lines at the start of your code:

from psychopy import serial
from struct import unpack

And to initialize the box:

s = serial.Serial('/dev/tty.usbserial-FT3ERKOD', 115200)

To erase all info in the box about previous button-presses:

s.flushInput()

To reset the button-box internal clock to 0:

s.write('e5')

Critically, the box records both the press and release of the button and sends a signal in exactly the same way (at least how it's set up now). To avoid this, you need to record both separately. In the attached file that shows how we tested the precision of the box relative to the computer clock, you can see how I did this. But basically, to check if a key has been pressed or released, you check this:

Retrieve a line triggered event from the box. We trigger a photodetector by drawing on the screen at a known time, and have the photodetector send an event into the box.

Problems

UPDATE: regarding the below problems, it's possible they're all avoided by using the new code that's since been developed at https://github.com/cedrus-opensource/pyxid
Hisham Abboud of Cedrus says "the code detects button presses and can retrieve the timestamp, but we're currently setting the timestamp to zero because there is some drift in the hardware itself. We will update the code once we know exactly what the time drift is and can compensate for it. The code is also capable of handling two devices at the same time, e.g. a response pad and an SV-1 voice key."

Any commands sent to button box occasionally needs to be done more than once before it takes. Box unreliable in this way (although apparently not a problem with code at github link above). Sometimes I have to restart code several times before box will listen

If send too long a stream of events (e.g. line in left on), box seems to become unresponsive

Sam T tried to do an experiment collecting multiple responses per trial, but seemed that the Cedrus RB-730 measured multiple responses inaccurately, accumulating a timing error of roughly 500ms over a 20-tap-piloting trial.